Drug delivery from stents

ABSTRACT

An intravascular stent has a coat comprising a crosslinked amphiphilic polymer and a sparingly water soluble matrix metalloproteinase inhibitor (MMPI). Preferably the polymer is formed from 2-methacryloyloxy-2′-ethyltrimethylammonium phosphate inner salt, C 4-18  alkyl methacrylate and reactive and/or crosslinking monomer and the MMPI is a hydroxamic acid, more preferably batimastat. Preclinical and clinical results are reported, showing good luminal areas and reduced intimal thickening.

CROSS-REFERENCE TO RELATED APPLICATION

This is a continuation application of U.S. application Ser. No.10/466,153, filed Jan. 7, 2004 now U.S. Pat. No. 7,713,538, which is aU.S. national phase application PCT application No. PCT/GB02/00103,filed Jan. 11,2002 the teaching of which is incorporated herein in itsentirety by reference.

BACKGROUND OF THE INVENTION

The present invention relates to the delivery of drugs from stentscoated with polymer. In particular the invention relates to delivery ofmatrix metalloproteinase inhibitors, for inhibition of restenosisfollowing stent implantation in the treatment of cardiovascular disease.

A leading cause of mortality within the developed world iscardiovascular disease. Coronary disease is of most concern. Patientshaving such disease usually have narrowing in one or more coronaryarteries. One treatment is coronary stenting, which involves theplacement of a stent at the site of acute artery closure. This type ofsurgery has proved effective in restoring vessel patency and decreasingmyocardial ischemia. However the exposure of currently used metallicstents to flowing blood can result in thrombus formation, smooth musclecell proliferation and acute thrombotic occlusion of the stent.

Non-thrombogenic and anti-thrombogenic coatings for stents have beendeveloped. One type of balloon expandable stent has been coated withpolymers having pendant zwitterionic groups, specificallyphosphorylcholine (PC) groups, generally described in WO-A-93/01221. Aparticularly successful embodiment of those polymers suitable for use onballoon expandable stents has been described in WO-A-98/30615. Thepolymers coated onto the stent have pendant crosslinkable groups whichare subsequently crosslinked by exposure to suitable conditions,generally heat and/or moisture. Specifically a trialkoxysilylalkyl groupreacts with pendant groups of the same type and/or with hydroxyalkylgroups to generate intermolecular crosslinks. The coatings lead toreduced thrombogenicity.

Fischell, T. A. in Circulation (1996) 94:1494-1495 describes testscarried out on various polymer coated stents. A thinner uniformpolyurethane coating, having a thickness of 23 μm was observed to have abetter performance than a relatively non uniform thicker layer having athickness in the range 75 to 125 μm. The thicker coatings are furtherdescribed by Van der Giessen, W J et al. in Circulation: 1996:94:1690-1697.

It has been suggested to utilise coatings on stents as reservoirs forpharmaceutically active agents desired for local delivery.

In U.S. Pat. No. 5,380,299 a stent is provided with a coating of athrombolytic compound and optionally an outer layer of ananti-thrombotic compound. The stent may be precoated with a “primer”such as a cellulose ester or nitrate.

Other drug containing stents and stent coatings are described by Topoland Serruys in Circulation (1998) 98:1802-1820.

McNair et al., in Proceedings of the International Symposium onControlled Release Bioactive Materials (1995) 338-339 describe in vitroinvestigations of release of three model drugs, caffeine, dicloxacillinand vitamin B12, from hydrogel polymers having pendant phosphorylcholinegroups. Alteration of the hydrophilic/hydrophobic ratio of the(hydrophilic) phosphorylcholine monomer 2-methacryloyloxyethylphosphorylcholine, (HEMA-PC) and a hydrophobic comonomer andcrosslinking of the polymer allows preparation of polymers having watercontents when swollen in the range 45 to 70 wt %. Crosslinking isachieved by incorporating a reactive monomer3-chloro-2-hydroxypropylmethacrylate. The tests are carried out onmembranes swollen in aqueous drug solutions at 37° C. The release ratesof the model drugs are influenced by the molecular size, solutepartitioning and degree of swelling of the polymer. Dicloxacillin isfound to have a higher half life for release than its molecular sizewould indicate, and the release profile did not appear to be Fickian.

McNair et al., in Medical Device Technology, December 1996, 16-22,describe three series of experiments. In one, polymers formed of HEMA-PCand lauryl methacrylate crosslinked after coating by unspecified meansare cocoated with drugs onto stents. Release rates of dexamethasone fromthe stent, apparently into an aqueous surrounding environment, wasdetermined. Drug release from cast membranes, as model coatings, showedthat the release rate obeyed Fickian diffusion principles, forhydrophilic solutes. In the third series of tests, a non-crosslinkedpolymer coating, free of drug, coated on a stent, had a significantdecrease in platelet adhesion when coated on a stent used in an ex-vivoarteriovenous shunt experiment. The stent coating method was notdescribed in detail.

Stratford et al in “Novel phosphorylcholine based hydrogel polymers:Developments in medical device coatings” describe polymers formed from2-methacryloyloxyethyl phosphorylcholine, a higher alkyl methacrylate,hydroxypropylmethacrylate and a methacrylate ester comonomer having areactive pendant group. These PC polymers were investigated to determinethe feasibility of delivering drugs and model drugs. Results are shownfor caffeine, dicloxacillin, vitamin B12, rhodamine and dipyridamole.The device on which the drug is coated is a guidewire that is, it is notan implant.

In EP-A-0623354, solutions of drug and polymer in a solvent were used tocoat Wiktor type tantalum wire stents expanded on a 3.5 mm angioplastyballoon. The coating weights per stent were in the range 0.6 to 1.5 mg.Coating was either by dipping the stent in the solution, or by sprayingthe stent from an airbrush. In each case coating involved multiplecoating steps. The drug was for delivery to the vessel wall. The drugssuggested as being useful for delivery from stents were glucocorticoids,antiplatelet agents, anticoagulants, antimitotic agents, antioxidants,antimetabolite agents and antiinflammatory agents. The worked examplesall use dexamethasone delivered from a bioabsorbable polymer.

In U.S. Pat. No. 5,900,246 drugs are delivered from a polyurethanecoated substrate such as a stent. The polyurethanes may be modified tocontrol its compatibility with lipophilic or hydrophilic drugs. Suitabledrugs are antithrombotic agents, antiinflammatory agents such assteroids, antioxidants, antiproliferative compounds and vasodilators.Particularly preferred drugs are lipophilic compounds. A polyurethanecoated stent is contacted with a drug in a solvent which swells thepolyurethane, whereby drug is absorbed into the polyurethane. Selectionof a suitable solvent took into account the swellability of thepolyurethane and the solubility of the drug in the solvent. It wasobserved that lipophilic drugs loaded in this way released more slowlyfrom hydrophobic polymer than more hydrophilic drugs, by virtue ofinteraction of the lipophilic drug with hydrophobic polymer.

In EP-A-0923953 coatings for implantable devices, generally stents,comprise an undercoat comprising particulate drug and polymer matrix,and an overlying topcoat which partially covers the undercoat. The topcoat must be discontinuous in situ, in order to allow release of thedrug from the undercoat. Examples of drugs include antiproliferatives,steroidal and non steroidal antiinflammatories, agents that inhibithyperplasia, in particular restenosis, smooth muscle cell inhibitors,growth factor inhibitors and cell adhesion promoters. The workedexamples use heparin and dexamethasone. The polymer of the undercoat is,for example, hydrophobic biostable elastomeric material such assilicones, polyurethanes, ethylene vinyl acetate copolymers, polyolefinelastomers, polyamide elastomers and EPDM rubbers. The top layer issuitably formed of non-porous polymer such as fluorosilicones,polyethylene glycols, polysaccharides and phospholipids. In theexamples, the undercoat comprised silicone polymer, and coating with thepolymer/drug mixture was carried out by spraying a suspension in whichboth drug and polymer were dispersed, followed by curing of the polymer.

In our earlier specification WO-A-0101957, unpublished at the prioritydate hereof, we describe methods for loading drugs into polymer coatedstents. The polymer coating preferably comprised a crosslinked copolymerof an ethylenically unsaturated zwitterionic monomer with a hydrophobiccomonomer. The drug was intended to be delivered into the wall of thevessel in which the stent was implanted and the thickness of the coatingon the stent was adapted so as to provide higher drug dosage on theouter surface of the stent. The drugs were selected fromantiproliferatives, anticoagulants, vasodilators, antiinflammatories,cytotoxic agents and antiangiogenic compounds.

It is well known to those who work in the area of surfactant chemistrythat it is possible to determine critical micelle concentrations by useof hydrophobic probes, which seek out the hydrophobic interior ofmicelles in preference to remaining in an aqueous environment. Pyrene isone such molecule. Moreover, the fluorescence intensities of variousvibronic fine structures in the pyrene molecules' fluorescence spectrumshows strong environmental effects based upon the polarity of thesolvent in which it is present (Kalyanasundaram, K. et al; JACC, 99(7),2039, 1977). The ratio of the intensity of a pair of characteristicbonds (I3:I1) is relevant to the environment. A value for I3:I1 of about0.63 is indicative of an aqueous environment whilst a value of about 1is indicative of hydrophobic environment.

Matrix metalloproteinases (or matrix metalloproteases) MMPs arezinc-binding endopeptidases involved in connective tissue matrixremodelling and degradation of the extra cellular matrix (ECM), anessential step in tumour invasion, angiogenesis and metastasis. TheMMP's each have different substrate specificities within the ECM and areimportant in its degradation. The analysis of MMP's in human mammarypathology showed that several MMP's are involved:collagenase (MMP1)which degrades fibrillar interstitial collagens; gelatinase (MMP2),which mainly degrade type IV collagen; stromelysin (MMP3) which has awide range of substrate activities.

Tissue inhibitors of metalloproteinase (T1MPs) represent a family ofubiquitous proteins which are natural inhibitors of MMPIs. TIMP-4 isthought to function in a tissue-specific fashion in ECM hemostasis.WO-A-00/53210 suggests that TIMP-4 may be useful in the treatment ofvascular diseases such as restenosis after balloon angioplasty. Localdelivery of the TIMP-4, or oligonucleotide encoding TIMP-4 is suggestedthrough injecting needles, or through a catheter used in an angioplastyintervention.

U.S. Pat. No. 5,240,958 describes a class of hydroxamic acid derivativesof oligopeptides which inhibit metalloproteinases that is are matrixmetalloproteinase inhibitors, MMPIs. The compounds are useful in themanagement of disease involving tissue degradation, especiallyrheumatoid arthritis, or other arthropathies, inflammation,dermatological disease, bone resorption and tumour invasion, as well aspromoting wound healing. Local delivery into a joint may be effected bydirect injection. One of the exemplified compounds is batimastat.Hydroxamic acid MMP1's are shown to promote tumour regression or inhibitcancer cell proliferation in WO-A0-93/21942. In WO-A-94/10990 suchcompounds are shown to inhibit tumour necrosis factor (TNF) production.

In WO-A-98/25597 MMPI's are used to prevent and treat heart failure andventricular dilation. In WO-A-99/47138, the use of MMPI's in combinationwith statins are used to treat vascular diseases, including inhibitingrestenosis. The delivery of the MMPI is systemic, although release maybe controlled. In WO-A-99/32150, MMPI's are used in combination with ACEinhibitors to slow and reverse the process of fibrosis, ventriculardilation and heart failure. In WO-A-00/04892 a combination of MMPI's andacyl-Co:Acholesterol acyltransferase (ACAT) are used to reduce smoothmuscle cell (SMC) and macrophage proliferation in atheroscleroticlegions.

In WO-A-95/03036 it is suggested that stents are coated withantiangiogenic drugs to inhibit tumour invasion. Examples ofantiangiogenic drugs include TIMP-1, TIMP-2 and metalloproteinaseinhibitors such as BB94 (batimastat). The antiangiogenic agent isdelivered from a polymeric carrier.

In U.S. Pat. No. 6,113,943 it is suggested that batimastat is anangiogenesis suppressor. It is delivered in that invention from a lacticacid polymer by sustained release.

In WO-A-00/56283, polymers having metal chelating activities are said tohave MMP inhibitory activity. The polymers may be coated onto a stent.It is suggested that MMP's contribute to the development ofatherosclerotic plaques and post angioplasty restenotic plaques. TheIVIMP inhibiting activity of the polymers is believed to be useful ininhibiting restenosis. The polymers may be coated onto a stent and mayhave additional pharmaceutically active agents dispersed therein, suchas MMPI's, including hydroxamic acids and, specifically, batimastat.Polymers having MMPI activity are capable of chelating divalent metals,and are generally polymers of unsaturated carboxylic acids althoughsulphonated anionic hydrogels may be used. One example of a monomer forforming a sulphonated anionic hydrogel isN,N-dimethyl-N-methacryloyloxyethyl-N-(3-sulphopropyl) ammonium betaine.Other examples of polymers are acrylic acid based polymers modified withC₁₀₋₃₀-alkyl acrylates crosslinked with di- or higher-functionalethylenically unsaturated crosslinking agents. There is no specificsuggestion of how to provide a coating on a stent comprising both MMPIactive polymer and additional therapeutic agent.

In WO-A-99/01118, antioxidants are combined with antineoplastic drugs toimprove their cytotoxicity. One example of the antineoplastic drug whoseactivity may be increased is batimastat. One utility of theantineoplastic combination is in the treatment of vascular disease. Thedrug combination may be administered from a controlled release system.

The crosslinkable polymer of 2-methacryloyloxyethyl-2′-trimethylammoniumethylphosphate inner salt and dodecyl methacrylate withcrosslinking monomer, coated onto a stent and cured, has been shown toreduce restenosis following stent delivery for the treatment ofatherosclerotic conditions. In WO-A-01/01957 mentioned above, we showthat a range of drugs may be loaded onto the polymer coated stents suchthat delivery of the drug into adjacent tissue takes place.

SUMMARY OF THE INVENTION

The present invention relates to a stent having a polymer coating, andcomprising a sparingly water soluble matrix metalloproteinase inhibitorwhich may be delivered over an extended period of time from the stentsafter placement.

A new intravascular stent comprises a metal body having a coatingcomprising polymer and a restenosis inhibiting agent in which therestenosis inhibiting agent is a sparingly water soluble matrixmetalloproteinase inhibitor (MMPI) and the polymer in the coating is acrosslinked amphiphilic polymer.

Preferably, on at least the outer wall of the stent the coatingcomprises a layer of the said amphiphilic polymer in which the MMPI isabsorbed. Additionally there may be MMPI absorbed into polymer in thecoating on the inner wall.

It may be possible to provide a sufficiently high does of MMPI on thestent in form of absorbed material. However, sometimes it may bedesirable to provide higher doses than may be loaded into theamphiphilic polymer matrix. For instance, it may be undesirable toincrease the level of polymer on the stent so as to be able to support ahigher loading of MMPI. In a preferred stent, the coating on the outerwall of the stent comprises an inner layer of the said amphiphilicpolymer, and, adhered to said inner layer, crystalline MMPI. Provisionof crystalline MMPI may also confer useful release characteristics onthe stent. The crystalline material may be controlled of a particlesize, for instance, to confer desired release characteristics whichcomplement the release of absorbed drug from the polymer coating.

In a preferred embodiment of the invention, the coating on at least theouter wall of the stent comprises an inner layer of the said amphiphilicpolymer and the top coat comprising a non-biodegradable, biocompatiblesemipermeable polymer. The semipermeable polymer is selected so as toallow permeation of MMPI through the top layer when the stent is in anaqueous environment. In such an environment, the semipermeable polymermay, for instance, be swollen, and it is in this form that it shouldallow permeation of the active MMPI. A topcoat may confer desirablecontrolled release characteristics. Its use is of particular value forthe preferred embodiment where coating comprises crystalline MMPIadhered to an inner layer of amphiphilic polymer. The topcoat in such anembodiment has several functions. It provides a smooth outer profile,minimises loss of MMPI during delivery, provides a biocompatibleinterface with the blood vessel after implantation and controls releaseof MMPI from the stent into the surrounding tissue in use.

A topcoat is preferably substantially free of MMPI prior to implantationof the stent.

A topcoat is preferably formed of a second cross-linked amphiphilicpolymer. The second amphiphilic polymer may be the same as the firstamphiphilic polymer.

In the present invention, an amphiphilic polymer comprises groupsconferring hydrophilicity and groups conferring hydrophobicity.Preferably the groups conferring hydrophilicity comprise zwitterionicgroups.

Preferably the polymer in the coating, when swollen with watercontaining pyrene, has hydrophobic domains observable by pyrenefluorescence intensity ratio I3:I1 of at least 0.8, preferably about 1.

Preferably the groups conferring hydrophobicity comprise pendanthydrophobic groups selected from C₄₋₂₄-alkyl, -alkenyl and -alkynylgroups any of which may be substituted by one or more fluorine atoms,aryl, C₇₋₂₄ aralkyl, oligo (C₃₋₄ alkoxy) alkyl and siloxane groups.

Most preferably the polymer is formed from ethylenically unsaturatedmonomers including a zwitterionic monomer and a hydrophobic comonomer.For forming a crosslinkable polymer, the ethylenically unsaturatedmonomers preferably include one or more reactive monomer having apendant reactive group(s) capable of forming intermolecular crosslinks.

Preferably the zwitterionic monomer has the general formula I:YBX  Iwherein

B is a straight or branched alkylene (alkanediyl), alkyleneoxaalkyleneor alkylene oligo-oxaalkylene chain optionally containing one or morefluorine atoms up to and including perfluorinated chains or, if X or Ycontains a terminal carbon atom bonded to B, a valence bond;

X is a zwitterionic group; and

Y is an ethylenically unsaturated polymerisable group selected from

CH₂═C(R)CH₂O—, CH₂═C(R)CH₂OC(O)—, CH₂═C(R)OC(O)—, CH₂═C(R)O—,CH₂═C(R)CH₂OC(O)N(R¹)—, R²OOCCR═CRC(O)O—, RCH═CHC(O)O—,RCH═C(COOR²)CH₂C(O)O—,

wherein:

R is hydrogen or a C₁-C₄ alkyl group;

R¹ is hydrogen or a C₁-C₄ alkyl group or R¹ is —B—X where B and X are asdefined above; and

R² is hydrogen or a C₁₋₄ alkyl group;

A is —O— or —NR¹—;

K is a group —(CH₂)_(p)OC(O)—, —(CH₂)_(p)C(O)O—,

—(CH₂), OC(O)O—, —(CH₂)_(p)NR³—, —(CH₂)_(p)NR³C(O)—,

—(CH₂)_(p)C(O)NR³—, —(CH₂)_(p)NR³C(O)O—, —(CH₂)_(p)OC(O)NR³—,—(CH₂)_(p)NR³C(O)NR³— (in which the groups R³ are the same ordifferent), —(CH₂)_(p)O—, —(CH₂)_(p)SO₃—, or, optionally in combinationwith B, a valence bond

p is from I to 12; and

R³ is hydrogen or a C₁-C₄, alkyl group.

In group X, the atom bearing the cationic charge and the atom bearingthe anionic charge are generally separated by 2 to 12 atoms, preferably2 to 8 atoms, more preferably 3 to 6 atoms, generally including at least2 carbon atoms.

Preferably the cationic group in zwitterionic group X is an amine group,preferably a tertiary amine or, more preferably, a quaternary ammoniumgroup. The anionic group in X may be a carboxylate, sulphate,sulphonate, phosphonate, or more preferably, phosphate group. Preferablythe zwitterionic group has a single monovalently charged anionic moietyand a single monovalently charged cationic moiety. A phosphate group ispreferably in the form of a diester.

Preferably, in a pendant group X, the anion is closer to the polymerbackbone than the cation.

Alternatively group X may be a betaine group (i.e. in which the cationis closer to the backbone), for instance a sulpho-, carboxy- orphosphor-betaine. A betaine group should have no overall charge and ispreferably therefore a carboxy- or sulpho-betaine. If it is aphosphobetaine, the phosphate terminal group must be a diester, i.e., beesterified with an alcohol. Such groups may be represented by thegeneral formula II—X¹—R⁴—N⁺(R⁵)₂—R⁶—V  II

in which X¹ is a valence bond, —O—, —S— or —NH—, preferably —O—;

V is a carboxylate, sulphonate or phosphate (diester-monovalentlycharged) anion;

R⁴ is a valence bond (together with X¹) or alkylene —C(O)alkylene- or—C(O)NHalkylene preferably alkylene and preferably containing from 1 to6 carbon atoms in the alkylene chain;

the groups R⁵ are the same or different and each is hydrogen or alkyl of1 to 4 carbon atoms or the groups R⁵ together with the nitrogen to whichthey are attached form a heterocyclic ring of 5 to 7 atoms; and

R⁶ is alkylene of 1 to 20, preferably 1 to 10, more preferably 1 to 6carbon atoms.

One preferred sulphobetaine monomer has the formula III

where the groups R⁷ are the same or different and each is hydrogen orC₁₋₄ alkyl and d is from 2 to 4.

Preferably the groups R⁷ are the same. It is also preferable that atleast one of the groups R⁷ is methyl, and more preferable that thegroups R⁷ are both methyl.

Preferably d is 2 or 3, more preferably 3.

Alternatively the group X may be an amino acid moiety in which the alphacarbon atom (to which an amine group and the carboxylic acid group areattached) is joined through a linker group to the backbone of polymer A.Such groups may be represented by the general formula IV

in which X² is a valence bond, —O—, —S— or —NH—, preferably —O—,

R⁹ is a valence bond (optionally together with X²) or alkylene,—C(O)alkylene- or —C(O)NHalkylene, preferably alkylene and preferablycontaining from 1 to 6 carbon atoms; and

the groups R⁸ are the same or different and each is hydrogen or alkyl of1 to 4 carbon atoms, preferably methyl, or two of the groups R⁸,together with the nitrogen to which they are attached, form aheterocyclic ring of from 5 to 7 atoms, or the three group R⁸ togetherwith the nitrogen atom to which they are attached form a fused ringstructure containing from 5 to 7 atoms in each ring.

X is preferably of formula V

in which the moieties X³ and X⁴, which are the same or different, are—O—, —S—, —NH— or a valence bond, preferably —O—, and W+ is a groupcomprising an ammonium, phosphonium or sulphonium cationic group and agroup linking the anionic and cationic moieties which is preferably aC₁₋₁₂ alkanediyl group.

Preferably W contains as cationic group an ammonium group, morepreferably a quaternary ammonium group.

The group W⁺ may for example be a group of formula—W¹—N⁺R¹⁰ ₃—W¹—P⁺R¹¹ ₃, —W¹—S⁺R¹¹ ₂ or —W¹—Het⁺ in which:

W¹ is alkanediyl of 1 or more, preferably 2-6 carbon atoms optionallycontaining one or more ethylenically unsaturated double or triple bonds,disubstituted-aryl, alkylene aryl, aryl alkylene, or alkylene arylalkylene, disubstituted cycloalkyl, alkylene cycloalkyl, cycloalkylalkylene or alkylene cycloalkyl alkylene, which group W¹ optionallycontains one or more fluorine substituents and/or one or more functionalgroups; and

either the groups R¹⁰ are the same or different and each is hydrogen oralkyl of 1 to 4 carbon atoms, preferably methyl, or aryl, such as phenylor two of the groups R¹⁰ together with the nitrogen atom to which theyare attached form a heterocyclic ring containing from 5 to 7 atoms orthe three groups R together with the nitrogen atom to which they areattached form a fused ring structure containing from 5 to 7 atoms ineach ring, and optionally one or more of the groups R¹⁰ is substitutedby a hydrophilic functional group, and

the groups R¹¹ are the same or different and each is R¹⁰ or a groupOR¹⁰, where R¹⁰ is as defined above; or

Het is an aromatic nitrogen-, phosphorus- or sulphur-, preferablynitrogen-, containing ring, for example pyridine.

Preferably W¹ is a straight-chain alkanediyl group, most preferablyethane-1,2-diyl.

Preferred groups X of the formula V are groups of formula VI:

where the groups R¹² are the same or different and each is hydrogen orC₁₋₄ alkyl, and e is from 1 to 4.

Preferably the groups R¹² are the same. It is also preferable that atleast one of the groups R¹² is methyl, and more preferable that thegroups R¹² are all methyl.

Preferably e is 2 or 3, more preferably 2.

Alternatively the ammonium phosphate ester group VIII may be replaced bya glycerol derivative of the formula VB, VC or VD defined in our earlierpublication no WO-A-93/01221.

Preferably the hydrophobic comonomer has the general formula VIIY¹R¹³  VIIwherein Y¹ is selected from

CH₂═C(R¹⁴)CH₂O—, CH₂═C(R¹⁴)CH₂OC(O)—, CH₂═C(R¹⁴)OC(O)—,

CH₂═C(R¹⁴)O—, CH₂═C(R¹⁴)CH₂OC(O)N(R¹⁵)—, R¹⁶OOCCR¹⁴═CR¹⁴C(O)O—,

R¹⁴—CH═CHC(O)O—, R¹⁴CH═C(COOR¹⁶)CH₂C(O)—O—,

wherein:

R¹⁴ is hydrogen or a C₁-C₄ alkyl group;

R¹⁵ is hydrogen or a C₁-C₄ alkyl group or R¹⁵ is R¹³;

R¹⁶ is hydrogen or a C₁₋₄ alkyl group;

A¹ is —O— or —NR¹⁵—; and

K¹ is a group —(CH₂)_(q)OC(O)—, —(CH₂)_(q)C(O)O—, (CH₂)_(q)OC(O)O—,

—(CH₂)_(q)NR¹⁷—, —(CH₂)_(q)NR¹⁷C(O)—, —(CH₂)_(q)C(O)NR¹⁷—,—(CH₂)_(q)NR¹⁷C(O)O—,

—(CH₂)_(q)OC(O)NR¹⁷—, —(CH₂)_(q)NR¹⁷C(O)NR¹⁷— (in which the groups R¹⁷are the same or different), —(CH₂)_(q)O—, —(CH₂)_(q)SO₃—, or a valencebond

p is from 1 to 12;

and R¹⁷ is hydrogen or a C₁-C₄ alkyl group;

and R₁₃ is the hydrophobic group.

In the comonomer of the general formula VII, the group R¹³ is preferablya hydrophobic group, preferably:

a) a straight or branched alkyl, alkoxyalkyl or oligoalkoxyalkyl chaincontaining 4 or more, preferably 6 to 24 carbon atoms, unsubstituted orsubstituted by one or more fluorine atoms optionally containing one ormore carbon double or triple bonds; or

b) a siloxane group —(CR¹⁸ ₂)_(qq)(SiR¹⁹ ₂)(OSiR¹⁸ ₂)_(pp)R¹⁹ in whicheach group R¹⁸ is the same or different and is hydrogen or alkyl of 1 to4 carbon atoms, or aralkyl, for example benzyl or phenethyl, each groupR¹⁹ is alkyl of 1 to 4 carbon atoms, qq is from 1 to 6 and pp is from 0to 49

Most preferably R¹³ is a straight alkyl having 4 to 18, preferably 12 to16 carbon atoms.

The reactive monomer to which provides crosslinkability preferably hasthe general formula VIIIY²B²R²⁰  VIIIwherein

B² is a straight or branched alkylene, oxaalkylene or oligo-oxaalkylenechain optionally containing one or more fluorine atoms up to andincluding perfluorinated chains, or B² is a valence bond;

Y² is an ethylenically unsaturated polymerisable group selected from

CH₂═C(R²¹)CH₂—O—, CH₂═C(R²¹)CH₂OC(O)—, CH₂═C(R²¹)OC(O)—,

CH₂═C(R²¹)O—, CH₂═C(R²¹)CH₂OC(O)N(R²²)—, R²³OOCCR²¹═CR²¹C(O)O—,

R²¹H═CHC(O)O—, R²¹H═C(COOR²³)CH₂C(O)O—

where R²¹ is hydrogen or C₁-C₄ alkyl;

R²³ is hydrogen, or C₁₋₄-alkyl group;

A² is —O— or —NR²²—;

R²² is hydrogen or a C₁-C₄ alkyl, group or R²² is a group B²R²⁰; p K² isa group —(CH₂)_(k)OC(O)—, —(CH)_(k)C(O)O—, —(CH₂)_(k)OC(O)O—,

—(CH₂)_(k)NR²²—, —(CH₂)_(k)NR²²C(O)—, —(CH₂)_(k)OC(O)O—,—(CH₂)_(k)NR²²—,

—(CH₂)_(k)NR²²C(O)—, —(CH₂)_(k)C(O)NR²²—, —(CH₂)_(k)NR²²C(O)O—, —

(CH₂)_(k)OC(O)NR²²—, —(CH₂)_(k)NR²²C(O)NR²²— (in which the groups R²²are the same or different), —(CH₂)_(k)O—, —(CH₂)_(k)SO₃—, a valence bondand k is from 1 to 12; and

R²⁰ is a cross-linkable group.

Group R²⁰ is selected so as to be reactive with itself or with afunctional group in the polymer (e.g. in group R¹³) or at a surface tobe coated. The group R²⁰ is preferably a reactive group selected fromthe group consisting of ethylenically and acetylenically unsaturatedgroup containing radicals; aldehyde groups; silane and siloxane groupscontaining one or more substituents selected from halogen atoms andC₁₋₄-alkoxy groups; hydroxyl; amino; carboxyl; epoxy; —CHOHCH₂Hal (inwhich Hal is selected from chlorine, bromine and iodine atoms);succinimido; tosylate; triflate; imidazole carbonyl amino; optionallysubstituted triazine groups; acetoxy; mesylate; carbonyl di(cyclo)alkylcarbodiimidoyl; isocyanate, acetoacetoxy; and oximino. Most preferablyR²⁰ comprises a silane group containing at least one, preferably threesubstituents selected from halogen atoms and C₁₋₄-alkoxy groups,preferably containing three methoxy groups.

Preferably each of the groups Y to Y² is represented by the same type ofgroup, most preferably each being an acrylic type group, of the formulaH₂C═C(R)C(O)-A, H₂C═C(R¹⁴)C(O)A¹ or H₂C═C(R²¹)O(O)-A², respectively.

Preferably the groups R, R¹⁴ and R²¹ are all the same and are preferablyH or, more preferably, CH₃. Preferably A, A¹ and A² are the same and aremost preferably —O—. B and B² are preferably straight chainC₂₋₈-alkanediyl.

Preferably the ethylenically unsaturated comonomers comprise diluentcomonomers which may be used to give the polymer desired physical andmechanical properties. Particular examples of diluent comonomers includealkyl(alk)acrylate preferably containing 1 to 24 carbon atoms in thealkyl group of the ester moiety, such as methyl (alk)acrylate or dodecylmethacrylate; a dialkylamino alkyl(alk)acrylate, preferably containing 1to 4 carbon atoms in each alkyl moiety of the amine and 1 to 4 carbonatoms in the alkylene chain, e.g. 2-(dimethylamino)ethyl (alk)acrylate;an alkyl (alk)acnylamide preferably containing I to 4 carbon atoms inthe alkyl group of the amide moiety; a hydroxyalkyl (alk)acrylatepreferably containing from 1 to 4 carbon atoms in the hydroxyalkylmoiety, e.g. a 2-hydroxyethyl (alk)acrylate glycerylmonomethacrylate orpolyethyleneglycol monomethacrylate; or a vinyl monomer such as anN-vinyl lactam, preferably containing from 5 to 7 atoms in the lactamring, for instance vinyl pyrrolidone; styrene or a styrene derivativewhich for example is substituted on the phenyl ring by one or more alkylgroups containing from 1 to 6, preferably 1 to 4, carbon atoms, and/orby one or more halogen, such as fluorine atoms, e.g.(pentafluorophenyl)styrene.

Other suitable diluent comonomers include polyhydroxyl, for examplesugar, (alk)acrylates and (alk)acrylamides in which the alkyl groupcontains from 1 to 4 carbon atoms, e.g. sugar acrylates, methacrylates,ethacrylates, acrylamides, methacrylamides and ethacrylamides. Suitablesugars include glucose and sorbitol. Diluent comonomers includemethacryloyl glucose and sorbitol methacrylate.

Further diluents which may be mentioned specifically includepolymerisable alkenes, preferably of 2-4 carbon atoms, eg. ethylene,dienes such as butadiene, ethylenically unsaturated dibasic acidanhydrides such as maleic anhydride and cyano-substituted-alkenes, suchas acrylonitrile.

Particularly preferred diluent monomers are nonionic monomers, mostpreferably alkyl(alk)acrylates or hydroxyalkyl(alk)acrylates.

It is particularly desirable to include hydroxyalkyl(alk)acrylates incombination with reactive comonomers which contain reactive silylmoieties including one or more halogen or alkoxy substituent. Thehydroxyalkyl group containing monomer may be considered a reactivemonomer although it also acts as a diluent. Such reactive silyl groupsare reactive with hydroxy groups to provide crosslinking of the polymerafter coating, for instance.

A particularly preferred combination of reactive monomers is {acute over(ω)}(trialkoxysilyl)alkyl(meth)acrylate and an {acute over(ω)}-hydroxyalkyl(meth)acrylate.

The monomers may, in some embodiments, comprise an ionic comonomer.Suitable comonomers are disclosed in our earlier publicationWO-A-9301221.

Preferably the zwitterionic monomer is used in the monomer mixture in amolar proportion of at least 1%, preferably less than 75%, morepreferably in the range 5 to 50%, most preferably 10-33%. Thehydrophobic comonomer is generally used in molar proportion of at least2%, preferably at least 5% or at least 10%, more preferably in the range15 to 99%, especially 50 to 95%, more especially 60 to 90%. Thecross-linkable monomer is preferably used in a molar amount in the range2 to 33%, preferably 3 to 20%, more preferably 5 to 10% by mole.

The zwitterionic polymer can be represented by the general formula IX:

in which I is 1 to 75, m is 0 to 99, n is 0 to 33 and m+n is 25 to 99,Y³ to Y⁵ are the groups derived from Y to Y², respectively, of theradical initiated addition polymerisation of the ethylenic group in Y toY², and

B and X are as defined for the general formula I,

R¹³ is as defined for the general formula VII, and

B² and R²⁰ are as defined for the general formula VIII.

In the preferred zwitterionic polymer in which Y, Y¹ and Y² are eachacrylic groups the polymer has the general formula X

in which B, X, R and A are as defined for the compound of the generalformula I, R¹⁴, A¹ and R¹³ are as defined for the general formula VII,R²¹, D², B² and R²⁰ are as defined for the general formula VIII and I, mand n are as defined for the general formula IX

The polymerisation is carried out using suitable conditions as known inthe art. Thus the polymerisation involves radical initiation, usingthermal or redox initiators which generate free radicals and/or actinic(e.g. u.v or gamma) radiation, optionally in combination withphotoinitiators and/or catalysts. The initiator is preferably used in anamount in the range 0.05 to 5% by weight based on the weight of monomerpreferably an amount in the range 0.1 to 3%, most preferably in therange 0.5 to 2%. The level of initiator is generally higher where themonomer includes reactive monomer and the polymer is cross-linkable,e.g. 1 to 20%.

The molecular weight of the polymer (as coated, where the polymer iscross-linkable) is in the range 1×10⁴ to 10⁶ Da, preferably in the range5×10⁴ to 5×10⁵ Da.

The monomer mixture may include a non-polymerisable diluent, forinstance a polymerisation solvent. Such a solvent may provide solubilityand miscibility of the monomers. The solvent may be aqueous ornon-aqueous. The polymer may be recovered by precipitation from thepolymerization mixture using a precipitating solvent, or recovery mayinvolve removal of any non-polymerisable diluent by evaporation, forinstance.

In the present invention the term sparingly water soluble means that atroom temperature the solubility of the compound in water is less than 1ml. The restenosis inhibiting agent is preferably a compound having alog P, where P is the octanol/water partition coefficient, of at least1.5 for instance more than 2.

The MMPI used in the present invention is preferably a hydroxamic acidbased collagenase inhibitor which is an oligopeptide compound,preferably of the general formula XI

wherein:

R³¹ represents a hydrogen atom C₁₋₆ alkyl, phenyl, thienyl, substitutedphenyl, phenyl(C₁₋₆)alkyl, heterocyclyl, (C₁₋₆)alkylcarbonyl, phenacylor substituted phenacyl group; or when a=0, R³¹ represents R^(x),wherein R^(x) represents a group:

R³² represents a hydrogen atom or a C₁₋₆ alkyl, C₁₋₆ alkenyl,phenyl(C₁₋₈) alkyl, cycloalkyl(—C₁₋₆)alkyl or cycloalkenyl(C₁₋₆)alkylgroup;

R³³ represents an amino acid side chain or a C₁₋₆ alkyl, benzyl, (C₁₋₆alkoxy)benzyl, benzyloxy(C₁₋₆ alkyl) or benzyloxbenzyl group;

R³⁴ represents a hydrogen atom or a methyl group;

a is an integer having the value 0, 1 or 2; and

A³ represents a C₁₋₆ hydrocarbon chain, optionally substituted with oneor more C₁₋₆ alkyl, phenyl or substituted phenyl groups;

or a salt thereof.

The term “amino acid side chain” means a characteristic side chainattached to the —CH(NH₂)(COOH) moiety in the following R or S aminoacids: glycine, alanine, valine, leucine, isoleucine, phenylalanine,tyrosine, tryptophan, serine, threonine, cysteine, methionine,asparagine, glutamine, lysine, histidine, arginine, glutamic acid andaspartic acid.

There are several chiral centres in the MMPI compounds because of thepresent of asymmetric carbon atoms. The presence of several asymmetriccarbon atoms gives rise to a number of diastereomers with theappropriate R or S stereochemistry at each chiral centre. Generalformula XI and, where appropriate, all other MMPI formulae in thisspecification are to be understood to include all such stereoisomers andmixtures (for example racemic mixtures) thereof. Compounds in which thechiral centre adjacent the substituent R³³ has S stereochemistry and/orthe chiral centre adjacent the substituent R³² has R stereochemistry arepreferred.

Preferably a hydrocarbon chain represented by A³ is a C₁₋₂-alkane diylgroup, most preferably a methane-diyl group;

R³¹ represents a hydrogen atom or a C₁₋₄ alkyl, phenyl, thienyl, benzyl,acetyl or benzoyl group;

R³² represents a C₃₋₆ alkyl (for example isobutyl) group;

R³³ represents a benzyl or 4-(C₁₋₆)alkoxyphenyl-methyl orbenzyloxybenzyl group;

R³⁴ represents a C₁₋₄ alkyl (for example methyl) group; and

R³⁵ represents a hydrogen atom.

Most preferably the MMPI is selected from batimastat [(2R-(1(S*),2R*,3S*))-N4-hydroxy-N1-(2-(methylamino)-2-oxo-1-(phenylmethypethyl)-2-(2-methylpropyl)-3-((thienylthio)methyl)butanediamide]and marimastat.

Preferably the MMPI should be present in an amount in the range 1 to1000 μg, preferably in the range 10 to 150 μg per stent.

Synthesis of compounds of the general formula XI is described in U.S.Pat. No. 5,240,958. Batimastat itself is synthesised in Example 2 ofthat document.

The stent may be made of a shape memory metal, or may be elasticallyself-expanding, for instance, be a braided stent. However, preferably itis a balloon expandable stent. In the preferred embodiment of theinvention, in which a topcoat is provided, the topcoat may be part of acoherent coating formed over both a stent and a stent delivery device,for instance a balloon of a balloon catheter from which a balloonexpandable stent is delivered. In this case, the balloon mayadditionally be provided with a coating comprising MMPI, for instanceadsorbed onto parts of its exterior surface between stent struts. Such adevice may be produced by loading the stent with MMPI after the stenthas been mounted onto the delivery catheter.

According to a further aspect of the invention there is provided a newmethod for producing a drug coated intravascular stent comprising thesteps:

a) a metallic stent body is coated on its inner and outer walls with across-linkable amphiphilic polymer;

b) the cross-linkable polymer is subjected to conditions under whichcross-linking takes place to produce a polymer-coated stent;

c) at least the outer coated wall of the polymer coated stent iscontacted with liquid drug composition comprising a sparinglywater-soluble matrix metalloproteinase inhibitor (MMPI) and an organicsolvent in which the MMPI is at least partially dissolved and which iscapable of swelling the cross-linked polymer of the coating, for a timesufficient to swell the polymer coating on the outer wall, to produce awet drug-coated stent;

d) organic solvent is evaporated from the wet stent to produce a drydrug-coated stent.

In the method of the invention, in step c), the MMPI May be bothabsorbed into the polymer and adsorbed at the process of the polymercoating whereby, upon evaporation of the solvent in step d) crystals ofMMPI are formed which are adherent to the surface of the dry drug coatedstent.

Alternative substantially all the drug may be absorbed into the polymer,or any surface drug may be rinsed off.

In the method of the invention, contact of the polymer coated stent withthe liquid MMPI composition may be by dipping the stent into a body ofthe stent, and/or by flowing, spraying or dripping liquid compositiononto the stent with immediate evaporation of solvent from the wet stent.Such steps allow good control of drug loading onto the stent, and areparticularly useful for forming the crystals of drug at the surface ofpolymer.

Whilst the stent may be provided with drug coating in the inventionprior to being mounted onto its delivery device, it is preferred, andmost convenient, for the stent to be premounted onto its delivery deviceprior to carrying out step c). By this means, it is primarily the outerwall of the stent (as opposed to the inner wall of the stent) whichbecomes coated with MMPI. Whilst this method will generally result inMMPI being coated onto the stent delivery section of the deliverycatheter, this is usually, not disadvantageous. In some circumstances itmay indeed be useful for the outer surface of the delivery catheter tobe provided with a coating of MMPI, which may be delivered to adjacenttissue upon placement of the stent in use. Generally the deliverycatheter is in contact with such tissue for a short period, wherebycontact is not maintained for a prolonged period, and limited level oftransfer of drug from the balloon takes place.

The method of the invention may include a step of applying a topcoat. Insuch a method a further step e) is carried out:

e) to at least the outer wall of the dry drug coated stent a polymer isapplied, to form a non-biodegradable, biocompatible, semi-permeablepolymer-containing top-coat.

In this preferred embodiment, in step e) it is preferred that a liquidtop-coating composition comprising polymer is coated onto at least theouter wall and is cured after coating to form the top-coat. It isdesirable for the liquid coating to be sprayed onto the outer wall ofthe stent, as this method has been found to minimise removal ofpreviously applied MMPI.

The top-coating composition, and consequently the top coat in theproduct, should generally be substantially free of MMPI. Preferably itis substantially free of other pharmaceutical actives although incertain circumstances it may be useful to cocoat a mixture of polymerand another pharmaceutically active agent.

For the embodiment of the invention where the liquid top-coatingcomposition comprises a cross-linkable polymer of the type preferred foruse to form the first amphiphilic polymer, the liquid top-coatingcomposition comprises crosslinkable polymer and the curing step in thepreferred method involves exposure of the top-coat to crosslinkingconditions.

Curing of crosslinkable polymer may involve exposure to irradiation,chemical curing agents, catalysts or, more usually raised temperatureand/or reduced pressure to acceptable condensation based cross-linkingreactions. Drying the liquid during composition usually involves raisedtemperature and/or reduced pressure for a time sufficient to reduce theamount of solvent remaining on the stent to undetectable levels orlevels at which it will not interfere with subsequent processing steps,or with release of the drug in use, or be toxic to a patient in whom thestent is implanted.

Where in the preferred method, the stent is preloaded onto its deliverydevice before being coated with MMPI, the top-coat is provided over boththe stent and the stent delivery section of the delivery catheter.Preferably the top-coat forms a coherent film covering the entire stentdelivery section. It is preferred for the device subsequently to besterilised and to be packaged into a sterile package for storage priorto use. Sterilisation may involve y irradiation, or application of heat,but preferably involves contact with ethylene oxide. We haveestablished, as shown in the worked examples below, that ethylene oxidetreatment following loading of drug results in retention of the MMPIcompound in a form in which it is indistinguishable,chromatographically, from starting MMPI. It is assumed that the compoundis not chemically modified and will have the same biological activity asthe starting MMPI applied to the stent.

Where, in the preferred method, a stent is contacted with liquid drugcomposition whilst mounted on a delivery device, it is important toensure that the said contact does not adversely effect the properties ofthe delivery catheter. For a balloon catheter, the contact must notsignificantly reduce the burst strength of the balloon. A preferredballoon catheter used for delivering a stent is formed of polyamide. Wehave established that contact of the balloon with ethanol, methanol ordimethylsulfoxide (DMSO) does not damage the balloon such that burststrength is reduced to an unacceptable level.

The solvent used in the liquid drug composition must be selected toallow adequate dissolution of MMPI, and to swell the crosslinked polymercoating to allow absorption of MMPI into the body of the polymer. MMPIwhich is absorbed into the polymer will be released over a period oftime after implantation of the stent. The liquid drug composition maycomprise other components, such as crystal modifiers, polymers, salts,acids, bases etc. It may be convenient to include dissolved amphiphilic,optionally crosslinkable polymer, to confer compatibility with thepolymer on the stent surface. Such a polymer may be identical to thatdescribed above used in the first aspect of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 compares the I3:I1 ratio from the fluorescence spectra of pyrenein different environments (Ref Ex. 1);

FIG. 2 shows the amount of pyrene retained in a variety of polymercoatings as determined in Reference Example 1;

FIG. 3 compares the fluorescence spectra of pyrene in laurylmethacrylate and water;

FIG. 4 compares the fluorescence spectra of pyrene in water and in twoamphiphilic polymers (Ref Ex 1)

FIG. 5 shows the actual and theoretical release rates of dexamethasonefrom polymers (Ref Ex 2)

FIG. 6 shows the elution rate for batimastat from polymer coated anduncoated stents release rate from the polymers based on its watersolubility (Example 1.1.2).

FIG. 7 shows the elution rate of batimastat in a flow model fromdifferent systems compared to the theoretical rate (Example 1.1.5).

FIGS. 8 a-d, 9 a-d and 10 a-d show the results of example 3; and

FIG. 11 shows the data explained in example 7.

DETAILED DESCRIPTION OF THE INVENTION

The present inventors have established that stents according to theinvention confer improved quantitative coronary angioplasty results whenused in animals, as compared to control polymer coated stents and thatthe stent is clinically useful in human trials.

The present invention is illustrated in the accompanying examples:

REFERENCE EXAMPLE 1

Zwitterionic polymer coatings were investigated by allowing pyrene todiffuse into the polymer and studying the degree to which it is takenup, and the effects on the ratio of the fluorescence band intensities tosee if there is any significant indication of the type of environmentpresent.

Polymer coatings of interest were dissolved in an appropriate solvent(usually ethanol) at 20 mg/ml⁻¹, The solution was used to coatpolymethylmethacrylate (PMMA) fluorescence cuvettes by simply pouringinto the cuvette, draining, following by an oven curing at 70° C.overnight. Polymers studied were:

a) a copolymer of 2-methacryloyloxy ethyl-2′-trimethyl-ammoniumethylphosphate inner salt (MPC):n-butylmethacrylate:hydroxypropylmethacrylate (HPM):trimethoxysilylpropylmethacylate (TSM) 29:51:15:5 (byweight)

b) a copolymer of MPC:benzylacrylate:HPM:TSM 29:51:15:5

c) a copolymer of MPC:dodecylmethacrylate (DM):HPM:TSM:45:35:15:5

d) a copolymer of MPC:DM:HPM:TSM:29:51:15:5

e) a copolymer of MPC:DM:HPM:TSM:15:65:15:5

f) poly(2-hydroxyethylmethacrylate).

The copolymers a-e were synthesised as disclosed in WO-A 9830615.

Analytical grade pyrene was used in high purity water (8.32×10⁻⁴ M). Thefluorescence spectrum was recorded using an excitation wavelength of 335nm and scanned from 350-440 nm on a PE LS 50B LuminescenceSpectrophotometer. Subtraction of the spectrum of each coating in waterwas necessary to remove the interference of a small band at 380 nmpresent in all methacrylate systems.

Environment information could be obtained by comparing the ratio of theintensity of the peaks at 373 nm (I1) and 383 nm (I3) (I3/I1). WhereI3/I1 was similar for polymer systems, the comparative amount of pyrenepresent could be estimated by the maximum intensity of I1;alternatively, the entire peak area may offer an alternative measure ofthe comparative amount of pyrene present in different coatings. It wasimportant to mark the side of the cuvette to ensure the sameorientations was achieved each time it was replaced in thespectrophotometer.

FIG. 1 compares the fluorescence spectra of pyrene in laurylmethaciylate (dodecyl methacrylate) (8.32×10⁻⁴ M) and water (8.32×M).For water the I3/I1 ratio is 0.633 (literature value 0.63) and the I3/I1ratio for lauryl methacrylate is 1.029. This indicates the verydifferent environments than might be expected to be seen within thepolymer coating.

Pyrene solution added to the coated cuvettes was allowed to stand for 16h, the cuvette emptied and washed thoroughly with ultrapure water,refilled with ultrapure water and the fluorescence spectrum recorded.The comparative maximum height of I1 was used to estimate the relativeamounts of pyrene in the coatings. This was repeated for three cuvettesof each polymer and the average taken. Despite some variations betweencuvettes, the trends were the same, indicating that the polymerformulations with more hydrophobic content seemed to contain more pyrene(FIG. 2). This is in contradiction to the water contents of thesematerials which vary in the opposite order. Hence for the varyingsystems, although water contents vary in the order c>d>f>e(88:40:38:27), the final fluorescence intensity (loading of pyreneachieved in the coating) varies according to e>d>c≧f. This indicatesthat the pyrene is preferentially associating itself with hydrophobicareas within the coating.

The ratio of I3/I1 was also studied (FIG. 3) and again, those polymerwith formal hydrophobic chains showed a greater ratio (indicating morehydrophobic environment for the pyrene). This polymer containing thebenzyl side chain has a lower than expected I3/I1, initially indicatingpoor interaction with the pyrene. However, measurement of the I3/I1 forpyrene in the pure benzyl acrylate monomer showed that the maximum I3/I1that could be expected would be 0.75 (i.e. less of a shift influorescent intensity is produced in this aromatic monomer compared tothe lauryl monomer). PHEMA coating showed I3/I1 characteristic of pyrenein an aqueous environment (FIG. 4), suggesting no formal hydrophobicdomain exists.

REFERENCE EXAMPLE 2 Drug-Polymer Interaction Versus Drug Solubility

There are examples of stent-based release of therapeutics that rely uponthe poor solubility of the active agent in water to achieve a slowrelease rate, i.e. by relying for extended release of drug on poorsolubility of the drug in water. When a graph of solubility versusrelease time (T90%) is plotted however, the relationship is extremelypoor (R²=0.006) indicating the solubility on its own does not accountfor the observed release characteristics.

This can be modelled further by comparing the theoretical release ofdrug into a known volume of water based purely upon its solubility andcomparing this with its actual release profile from the polymer systeminto the same elution volume. Assuming that 100 μg of the drug is placeon a surface, and that the drug is eluted off into 5 ml of solution, andthen at various arbitrary points, 1 ml removed, and 1 ml of freshsolution added, the dissolution profiles for various drugs could becalculated and compared to experimental data obtained the same way. Thevariation between calculated and observed could be attributed to theinteraction with the polymer matrix.

This is clearly illustrated by FIG. 4. Here, the theoretical release ofdexamethasone (which has a log P where P is the partition coefficientsof 2.55) has been calculated and plotted on the graph (circles) based onthe solubility of the compound and the volume of water into which it isbeing eluted. The difference between this line and the observed data(squares) is the degree of interaction of the compound with thehydrophobic domains within the polymer coating which in this case ispolymer d) from Ref. Example 1. It is the interaction that prolongs therelease of the compound and offers some capability to control thedelivery of the drug to its surrounding environment.

EXAMPLE 1

1.1.1 Drug Uptake Studies

The solubility of batimastat was tested in ethanol (100%) prior to stentloading investigations. This was by preparation of a series of solutionsoutlined in Table 1

TABLE 1 Solubility of Batimastat in Ethanol Batimastat Concentration inethanol (100%)/mg per ml Solubility 2.6 white suspension 1.13 finesuspension 1.05 clear suspension

BiodivYsio DD stents provided with a cross-linked coating on both innerand outer walls of copolymer d) used in Reference Example 1 wereprovided with a coating of drug in the following manner:

1) Stents were immersed in the drug solution for 5 minutes.

2) Stents were removed from the solution and wick dried on tissue.

3) The stents were allowed to dry for at least 1 hour at roomtemperature.

DD stents were loaded for 5 minutes. The drug total loading was measuredby HPLC, see section 1.2.3. Non-polymer coated stents were tested ascontrols. The results are shown in section 1.2.1.

1.1.2 Batimastat Elution Studies at 25° C. and 37° C.—Non Flow System

Elution studies were carried out at 25° C. for up to 1 hour in gentlyagitated PBS. This was done by placing DD stents loaded with batimastat,from section 1.1.1, individually in vials containing 5 ml phosphatebuffered saline (PBS) on rollers. At various time intervals a I mlaliquot was removed and replaced with 1 ml fresh PBS. The stents andwater aliquots were measured, see section 1.1.4, to give the amount ofdrug eluted and the amount of drug remaining on the stents, see section1.2.1 for results.

1.1.3 Elution Studies in Flow-System

Next, the elution of batimastat was examined in a flow system at 37° C.and evaluated over a 2 day period using the best loading conditions. PBSwas maintained at 37° C. in six stirred reservoirs (500 ml each) withina water bath. A length of silicone tubing (3 mm internal diameter) wasattached from each reservoir to one of six stent chambers (4 mm internaldiameter 80 mm long) and back to the respective reservoir via aperistaltic pump. The system was pumped using a flow rate of 100 ml/minto reach equilibrium temperature of 37° C. The flow was stopped and twobatimastat loaded stents were placed in each of the six stent chambers,and flow recommenced. A stent was then removed at various time periodsand wick dried. These were used to measure the amount of batimastatremaining on the stent. This was continued over a 48 hour period. Seesection 1.2.3 for results.

1.1.4 Analytical Determination of Drug Loading on DD Stents and DrugEluted

The following method conditions were used for the HPLC analysis ofbatimastat:

Mobile Phase Methanol: Water 65.35 (v/v) + 0.15% TFA Column PhemomenexLuna C8, 250 cm × 6 mm × 3 μm Flow Rate 0.8 ml/min Detection UV  © 214nm Injection Volume 100 μL Run Time 8 minutes

104.5 mg batimastat was placed in a 100 ml flask and dissolved inmethanol to give a 1045 ppm stock solution. The batimastat stocksolution was serially diluted to give solutions with the nominalconcentrations of 10.45, 5.23, 1.05, 0.52, 0.11, 0.05 and 0.01 ppm. Allsolutions were made up to volume with the mobile phase.

The linearity to of the system was tested by injecting each solutiontwice and a diluent blank. The repeatability of the system was tested byinjecting the 10.45, 1.45 and 0.11 ppm solutions 6 times.

To determine the total loading on DD stents, one stent was placed in 3.0ml of mobile phase and sonicated for 1 hour. The resulting solution wasmade up to 5.0 ml with mobile phase and the resulting solution injectedonto the system.

Samples of eluent from elution studies were injected directly into thesystem. The sensitivity of the method was 0.010 ppm (0.010 μg/ml).

1.1.5 Assessment of Changing Solvent on DD Stent Delivery System

In order to load the pre-mounted (on a balloon delivery catheter) DDstent with batimastat, the stent/delivery system combination must beimmersed in the drug solution. The aim of this experiment was to checkif the solvent had a detrimental effect on the balloons. Pre-mountedBioDivYsio stents were placed in solvent for minutes then allowed to airdry for 47 minutes. The mechanical properties of the balloon were thenassessed by a burst pressure test.

The samples were connected to a pressure pump and gauge and a positivepressure of 1 atm. (10⁵ Pa) applied and left for 30 seconds. Thepressure was increased by 1 atm (10⁵ Pa) every 30 seconds until thestent was fully deployed i.e. there were no creases or folds in theballoon.

The pressure was then increased to 16 atm. (16×10⁵ Pa) which is therated burst pressure for the balloon system, and held for 30 seconds.The pressure was then increased in 1 atm. steps and held for 30 secondsat each step, until the balloon burst. The results are in section 1.2.4.

1.1.6 Batimastat Uptake on Balloon Pre-Mounted DD Stents

Using the optimum loading conditions, see section 1.2.1, a loading trialwas carried out on balloon mounted stents in preparation for implantstudies in pigs.

The pre-mounted stent was unsheathed and loaded for 5 minutes in 1 ml of6 mg/ml batimastat in methanol, from a 1 ml syringe. The loaded syringewas pushed onto the pre-cut catheter hoop to immerse the premountedstent, ensuring the whole stent was immersed. After 5 minutes thesyringe was removed and the stent allowed to dry for 5 minutes at roomtemperature. The balloon was then inflated slowly, and the stentremoved. For drug uptake results see section 1.2.5.

1.2 Results

1.2.1 Drug Uptake on PC Coated Stents

The amount of batimastat on the 15 mm DD stents were measured afterloading for 5 minutes, see Table 2.

TABLE 2 Drug Uptake on PC Coated Stents and Uncoated Stents BatimastatConcentration/ Batimastat Total Loading/μg per Stent mg per ml DrugSolvent Coating (no. of stents measured) 1.05 Ethanol Yes  5.4 ± 0.6(3)6.03 Methanol Yes 35.1 ± 2.1(3) 50.0 DMSO/EtOH Yes 193.1 ± 13.2(3) 90:1010.0 DMSO/EtOH Yes 43.3 ± 0.7(3) 10:90 10.0 DMSO/EtOH None 39.8 ± (3)  10:90 10.0 DMSO/EtOH None 49.9 ± 7.1(3) 10:90

Loading from ethanol resulted in only a small amount of uptake ofbatimastat onto the stents. From previous experience increasing the drugloading concentration increased drug uptake. Since ethanol was used asits highest concentration then alternative solvents were required.

Methanol showed a good increase, however a loading greater then 50 μgper stent is preferred. Examination by Scanning Electron Microscopy(SEM) showed good coverage of the stent with single fibre batimastatcrystals on the surface.

A combination of 90:10 DMSO and ethanol was tried, which resulted in avery large increase in drug loading. However SEM showed gross webbing ofthe drug between the stent struts as a mesh of fibres. Reducing theconcentration to 30 and 10 mg/ml did not reduce the amount of webbing.

To overcome this level of DMSO was reduced to reduce the amount ofwebbing and improve the rate of drying since DMSO evaporates more slowlythan ethanol at room temperature. 10 mg/ml batimastat in 10:90DMSO/ethanol gave good packing of the drug on the stent without webbing.

The drug was more tightly packed and structured as crystals with manytendrils compared to the single fibres when loaded from methanol.

Uncoated stents gave an uptake of 40 μg per stent which is equivalent toPC1036 coated stents loaded under the same solvent conditions. The drugwas also observed by SEM on the uncoated stents.

To reduce the amount of excess drug crystallised on the coating surfacea wash step was included in the loading process. Unmounted stents wereloaded as described in section 5.1 from 6 mg/ml batimastat in methanol.After loading one set of stents was dipped in methanol for 5 secondsbefore drying and a second set after drying, see Table 3. This suggeststhe washing process was too rigorous, removing all the drug, not justthe excess.

TABLE 3 Effect of Wash Step on Drug Loading Total Loading/μg per StentLoading Process (no. of stents measured) Standard 35.1 ± 2.1 (3)  PreDrying Wash  0.1 ± 0.03 (3) Post Drying Wash 0.1 ± 0.1 (3)

1.2.2 Drug Elution Studies

The elution of batimastat from 3 stents loaded for 5 minutes in 1.05mg/ml batimastat in ethanol was measured over 15 minutes at roomtemperature in PBS, see FIG. 6 for results.

Due to poor total loading from ethanol, the elution of drug was measuredover an extended period using stents loaded from methanol, see FIG. 6.Batimastat showed good controlled release over 1 hour. The rate ofelution was not restricted by the 5 ml into which the drug was elutedsince the amount of drug measured per time point in PBS continued toincrease. Only 70% of the drug was accounted for after elution whenloaded from methanol. Based on the total amount loaded, 44% ofbatimastat remained on the stents after 1 hour.

From section 1.2.1 better loading was obtained using 10 mg/mlDMSO/ethanol 10:90. It was noted that uncoated stents gave equivalentdrug uptake to coated stents. Therefore the elution of uncoated stentsloaded from 10 mg/ml batimastat in DMSO/ethanol 10:90 was measured over15 minutes, leaving 80% batimastat on the stents. Therefore the elutionfrom both coated and uncoated stents was measured over a longer timespan to determine the benefit of the PC polymer.

1.2.3 Elution in Flow Model

10 mg/ml batimastat in DMSO/ethanol 10:90 gave slightly better loadingthan methanol therefore these were placed in the flow model at 37° C.,see FIG. 7. The drug released steadily over 6 hours at 37° C. After 6hours more than 99% of the batimastat had eluted from the stent. Thisexperiment was repeated on uncoated stents. FIG. 7 shows that 98%batimastat eluted from the stents in 1 hour.

The initial 1 hour elution profile of the coated stent is similar to theuncoated, FIGS. 6 & 7. This may be due to the elution of excess drug onthe surface as observed by SEM and the prolonged elution being a resultof release of drug entrapped in the coating. The profile in File 7 showsthe theoretical release, which would be expected if there was nointeraction with the polymer. The fact that this is faster than theactual indicates that there is an interaction. This is believed to bedue to hydrophobic interactions between the hydrophobic batimastatmolecules and the domains illustrated by the pyrene fluorescence fastdescribed in Reference Example 1.

In vivo, the elution of batimastat from the stents may be slower thanindicated in this experiment due to the physical presence of the vesselwall. A concentration gradient may be set up between the drug in thestent and in the vessel wall which may also slow the rate of elution.

1.2.4 Balloon Burst Test Results

Three pre-mounted BioDivYsio stents were assessed in methanol and DMSO,see Table 4.

TABLE 4 Effect of Drug Loading Solvent on Balloon Burst Pressure SolventDeployment Pressure/atm. Burst Pressure/atm. None 3 >16 Ethanol 3 >16Methanol 3 23 ± 1 DMS0 3 24 ± 1

Neither solvent causes detrimental effects on the balloon. The choice ofdrug loading solvent is therefore related to drying rate and solventtoxicity.

1.2.5 Uptake of Batimastat on Balloon Pre-Mounted Stents

The amount of batimastat on the 18 mm pre-mounted stents was measuredafter inflation, see Table 5 for results. The stents were loaded from a6 mg/ml batimastat in methanol solution.

TABLE 5 Batimastat on Expanded Pre-Mounted DD Stents Total Loading /μgper stent /μg per balloon Drug Loading Loading (no. of stents (no. ofballoons time/minutes Conditions measured) measured) 5 Standard  24.6 ±10.1 (3) 23.2 ± 1.2 (3) 5 Loaded Twice 20.1 ± 1.2 (3)  45.6 ± 12.7 (3)30 Longer Loading 23.2 ± 8.8 (3) 19.2 ± 1.9 (3) 5 Additional 108.5 ± 6.0(3)  126.7 ± 32.6 (3) 2 × 15 ul Drops

Using standard loading conditions gave loading similar to unmountedstents, see Table 2. To increase this several trials were made, firstlyby repeating the loading process after initial loading, and secondlytrying an increase in loading time of 30 minutes. Neither showed anincrease in drug uptake, see Table 5.

Next additional loading solution was applied as droplet after thestandard loading process, this way the drug could not redissolve fromthe stent. Using a micro-line pipette (Gilson type) a 15 μl aliquot ofthe drug loading solution was placed onto the stent. The drop of drugsolution was spread along the stent. The stent was allowed to dry for 1minute, then repeated with 15 μl to give a total addition of 30 μl.

The increased loading was equivalent to the amount of drug added asdrops, shared equally between the stent and balloon, see Table 5.

1.3 Conclusions

The coat loading of batimastat on PC polymer coated stents was improvedby using higher concentration of drug in the liquid compositions. This,in turn, requires changing from ethanol to either methanol or acombination of DMSO and ethanol, in which batimastat is more soluble.

The elution of batimastat was at a controlled rate, with 99% beingremoved from the stent after 6 hours at 37° C., in the flow system. Thisperformance matches predictions from the value for the partitioncoefficient. Batimastat has a calculated log P of 2.45.

EXAMPLE 2 Effects of Sterilisation

Stents provided with one top-coating layer (formed by applying asolution of polymer d) in ethanol to the drug loaded stent mounted on aballoon stent delivery catheter) were subjected to ethylene oxide'treatment, under sterilisation conditions. Subsequently the ethyleneoxide treated stent and non-ethylene oxide treated stents were testedfor the level of drug after inflation, using the general technique ofExample 1.1.4 and using HPLC, 1H and ¹³C NMR and polarimetry. Theresults indicate that the level of drug detected by this method for thepost ethylene oxide treated product was not significantly different fromthe pre-treated product. The HPLC, NMR and polarimetry results indicatethat the batimastat has not been adversely affected by the ethyleneoxide treatment.

EXAMPLE 3 Re-Endothelialisation of Batimastat-Loaded BiodivYsio Stents

BiodivYsio stents (control, low dose batimastat and high dosebatimastat) were implanted into healthy farm swine. After 5 days theanimals were sacrificed and the stents studied for endothelialisationusing scanning electron microscopy. It was found that batimastat-loadedonto 15 mm BiodivYsio stents at either low or high dose concentrations,34.2±1.6 and 115.3±16.1 μg batimastat per stent (equivalent to 0.43±0.02and 1.43±0.20 μg per mm² of stent) respectively, did not affect theendothelialisation process in-vivo at 5 days. The drug-loaded stentsshowed continuous and confluent layers of endothelia and were comparableto the control stents without drug.

The stents were implanted into the coronary arteries of farm swine (2per animal, each in different arteries). After sacrifice, the vesselswere excised and trimmed of all extraneous tissue, washed in buffer, andfixed in 2.5% glutaraldehyde at pH 7.4. Fixation was carried out for aminimum of 24-48 hours in 2.5% glutaraldehyde. The section of artery wasrinsed in 0.1 M cacodylate buffer pH 7.4. The arteries were shipped in0.1 M cacodylate buffer pH 7. The vessels were required to be leftwhole, i.e. without longitudinal transection. A small V was marked inthe proximal end of the vessel to determine vessel orientation. SEManalysis was carried out on three sections of the stented artery and at2 different magnifications (high and low). The analysis concentrated onthe rate and extent of re-endothelisation of the stent struts and thepresence of any cellular/biological debris within the stented segment ofartery.

Some typical results for control, low dose and high dose stents areshown in FIGS. 8-10.

FIGS. 8 a-8 d show SEM results from the control stent (polymer coated,no drug).

FIG. 8 is a 13× magnification of the distant end (relative to thesurgeon) of the stated vessel which FIG. 8 b is a 13× magnification ofthe proximal end of the stented vessel. FIG. 8 c is a 259 timesmagnification of the luminal surface proximal to the stent and FIG. 8 dis a similar area at 2190× magnification which shows endothelial andsome white blood cells.

FIG. 9 a-d show SEM results for the low dose batimastat loaded stent.FIGS. 9 a and 9 b correspond to FIGS. 8 a and b, respectively at thesame magnification. FIG. 9 c shows the luminal surface proximal to stentat 135 times and FIG. 9 d is a higher magnification (1800×) of the samearea.

FIG. 10 a-d show SEM results for the high dose batimastat loaded stent.FIGS. 10 a and b corresponds to and are at the same magnification asFIG. 8 a and b, respectively. FIG. 10 c shows the endothetial surfacebetween the struts at the proximal end at 320× magnification and FIG. 10d shows the same area at 2150× magnification, showing white blood cellsand a macrophage on endothelial cells.

EXAMPLE 4 Pharmacokinetic Study (PK)

The pharmacokinetic studies were initiated to investigate the depositionof drug from the batimastat-loaded BiodivYsio stent. These studies usedthe well established New Zealand white rabbit model where ¹⁴Cbatimastat-loaded BiodivYsio stents were placed in the left and rightiliac arteries and levels of batimastat deposited in the iliac arteriesand solid organs were measured twenty eight days after stentimplantation.

The study demonstrated the reproducible release and deposition of drugfrom the BiodivYsio Batimastat stent. First order release was observedsuch that the bulk of loaded drug (94%) was eluted 28 dayspost-implantation. Drug released from each stent was primarily localizedto the 15 mm long stented region, and to a lesser degree the adjacentadventitia, and regions immediately proximal and distal to the stent.The data followed the expected patterns of release and deposition andindicated that there is unlikely to be any long term issue of residualdrug within the arterial wall after release is complete.

Very little of the drug was found in the distal organs (brain, liver,kidney, spleen, carotid artery, gonad, heart, lung, and intestine), thenumbers detected being so low they were considered to be within thebackground noise level of the assay, and for all intents and purposes tobe considered as undetectable.

EXAMPLE 5 One-Month Pre-Clinical Assessment in Farm Swine

A total of 24 stents were implanted in 12 farm swine pigs for 1 month.Two doses were assessed: 0.30±013 μg batimastat per mm² of stent surfacearea, was obtained using a dip loading process prior to implantation;the higher dose of 1.09±0.06 μg batimastat per mm² of stent, wasobtained using an additional loading process. The higher dose was set atthe maximum quantity that could be loaded onto the stent. Analysis ofthe Quantitative Coronary Angiogram (QCA) and histomorphometric resultsshow that there was a significant difference between the intimal areafor the low dose of batimastat compared to the control (2.5 vs 4.0).Histological examination confirmed that all the vessels were patent,without the presence of thrombus in the vessel lumen. All sectionsshowed stent struts to be completely covered, leading to a smoothendoluminal surface. There was no excessive inflammatory response atstent struts in BiodivYsio Batimastat treated sections compared to thecontrol sections. Medial and adventitial layers appeared similar in allthree groups. The perivascular nerve fibers, the adipose tissue andadjacent myocardium appeared normal in control and BiodivYsio Batimastattreated sections. Therefore this study demonstrated that the BiodivYsioBatimastat stent with low and high dose was well tolerated up to 28days, low dose demonstrating some anti-restenotic potential.

EXAMPLE 6 3-Month Pre-Clinical Evaluation in Yucatan Minipigs

The 3 month data from a short and longer-term safety study on Yucatanminipigs using two doses of batimastat, 0.03±0.01 (low dose) and0.30±0.13 μg (high dose) batimastat per mm² of stent showed someefficacy.

In the control group it was found that the stenosis rate was 34% (QCAanalysis). After 3 months a trend in favour of the treatment groups wasfound, with an indication of a dose-response relationship shown in FIG.5. The stenosis was reduced by 20% and 34% in the low and high dosegroups respectively compared to the control. However this difference wasnot statistically significantly different (p=0.15 ANOVA analysis).

EXAMPLE 7 Batimastat Delivered Per mm² of the Coronary Artery VesselWall

As the dose per stent is fixed, the quantity of batimastat delivered permm² of coronary artery vessel wall is dependent upon the diameter of thevessel. The data in FIGS. 11-11 c demonstrate the calculated quantity ofbatimastat that can be delivered per mm² of vessel wall from theBiodivYsio Batimastat LV & SV stents (LV=large vessel 3-4 mm deployed;SV=small vessel 2-3 mm deployed). In the calculation of vessel wallsurface area it has been assumed that the vessel wall is a cylinder witha uniform cross-section.

The data show that the mean quantity of batimastat delivered from an 18mm SV stents is within the range of 0.09-0.22 μg/mm²/vessel wall, whichis in line with the mean quantity of batimastat delivered from similarlength BiodivYsio LV stent which is within the range of 0.07-0.21μg/mm²/vessel wall.

EXAMPLE 8 Clinical Trial Assessment—30 Day Data for First 30 Patients

Batimastat anti-restenosis trial utilising the BiodivYsio Local DrugDelivery PC-stent (BRILLIANT-EU) which is a mutli-centre prospectivestudy performed at 3 centres in France and 3 centres in Belgium with 170patients. The primary objective of this study was to evaluate theoccurrence of MACE (death, recurrent myocardial infarction or clinicallydriven target lesion revascularisation) to 30 days post procedure inpatients who received a BiodivYsio batimastat stent. The secondaryobjectives were to evaluate: Incidence of sub(acute) thrombosis, binaryrestenosis and other QCA endpoints. 11, 15, 18, 22 and 28 mm BiodivYsiobatimastat stents by 3.0 to 4.0 mm in diameter were under investigation.

30 day data for the first 30 patients are reported in this example.Other endpoints have not yet been reached and therefore will not bedescribed.

31 patients (87% male) with an average height of 170 cm and weight of 78Kg were enrolled into the study. 52% of patients had a history ofhypercholesterolaemia and 78% had smoked or were current smokers. 74% ofpatients had single vessel disease and 32% had a history of previous MI.The vessel/lesion characterisations were as follows:

Vessel Treated Lesion Classification RCA 35% A 26% LAD 48% B1 35% Cx  9%B2 26% Other  6% C 13%

The mean lesion length treated was 12 mm. The majority of patients hadeither a 15 mm (42%) or an 18 mm (29%) stent implanted. The stent wasadequately positioned in all patients, there were no cases of deliveryballoon rupture or stent embolisation. There were no MACE resulting fromthe angioplasty or stenting procedure.

At 30 day follow-up one patient had a MACE (patient 12 died 21 days postprocedure) and 3 patients had serious adverse events that were unrelatedto the study treatment (Table 6).

There were no reported cases of sub(acute) thrombosis.

There were no significant changes in blood parameters either immediatelypost procedure or at 30 day follow-up (other than those that would beexpected as a result of the interventional procedure e.g. elevated CKlevels).

Technical device success defined as intended stent successfullyimplanted as the first stent was 100%. Clinical device success definedas technical device success in the absence of MACE to discharge was alsoachieved in all patients.

Pharmacokinetic studies have shown that ˜95% of the batimastat will havebeen eluted from the PC coating after 28 days (Example 4). Therefore thedata presented in this initial interim analysis suggest that thepresence of batimastat in the coating is not associated with anincreased occurrence of MACE or serious adverse events and that theBiodivYsio Batimastat stent is safe in the short term for use inpatients.

TABLE 6 Patients with Major Adverse Cardiac Events (MACE) - SafetyAnalysis Set In Hospital Up to 30 days follow-up Major Adverse Number(%) Number of Number (%) Number of Cardiac Event of patients events ofpatients events Cardiac death 0 (0) 0 1 (3) 1 Q-wave MI 0 (0) 0 0 (0) 0Non Q-wave MI 0 (0) 0 0 (0) 0 CABG 0 (0) 0 0 (0) 0 Repeat angioplasty 0(0) 0 0 (0) 0 TOTAL 0 (0) 0 1 (3) 1

1. An intravascular stent comprising a metal body having a coatingcomprising polymer and a restenosis inhibiting agent in which therestenosis inhibiting agent is a sparingly water soluble matrixmetallo-proteinase inhibitor (MMPI) and the polymer in the coating is across-linked amphiphilic polymer formed from a crosslinkable polymer offormula IX

wherein l is 1 to 75, m is 0 to 99, n is 0 to 33 and m+n is 25 to 99,Y³, Y⁴, and Y⁵ are the groups derived from Y, Y¹, and Y² respectively,of the radical initiated addition polymerisation of the ethylenic groupin Y, Y¹, and Y², wherein Y, Y¹, and Y² are independently selected fromthe group consisting of

CH₂═C(R)CH₂O—, CH₂═C(R)CH₂OC(O)—, CH₂═C(R)OC(O)—, CH₂═C(R)O—,CH₂═C(R)CH₂OC(O)N(R¹)—, R²OOCCR═CRC(O)O—, RCH═CHC(O)O—,RCH═C(COOR²)CH₂C(O)O—,

wherein: R is hydrogen or a C₁-C₄ alkyl group; R¹ is hydrogen or a C₁-C₄alkyl group or R¹ is —B—X; R² is hydrogen or a C₁₋₄ alkyl group; A is—O— or —NR¹—; K is a group selected from the group consisting of—(CH₂)_(p)OC(O)—, —(CH₂)_(p)C(O)O—, —(CH₂)_(p)OC(O)O—, —(CH₂)_(p)NR³—,—(CH₂)_(p)NR³C(O)—, —(CH₂)_(p)C(O)NR³—, —(CH₂)_(p)NR³C(O)O—,—(CH₂)_(p)OC(O)NR³—, —(CH₂)_(p)NR³C(O)NR³— (in which the groups R³ arethe same or different), —(CH₂)_(p)O—, —(CH₂)_(p)SO₃—, or, optionally incombination with B, a valence bond; p is from 1 to 12; R³ is hydrogen ora C₁-C₄, alkyl group; B is a straight or branched alkylene (alkanediyl),alkyleneoxaalkylene, alkylene oligo-oxaalkylene chain optionallycontaining one or more fluorine atoms up to and including perfluorinatedchains, or a valence bond; B² is a straight or branched alkylene,oxaalkylene, oligo-oxaalkylene chain optionally containing one or morefluorine atoms up to and including perfluorinated chains, or a valencebond; X is a zwitterionic group; R¹³ is a hydrophobic group; and R²⁰ isa cross-linkable group.
 2. The stent according to claim 1 in which on atleast the outer wall of the stent the coating comprises a layer of thesaid amphiphilic polymer in which the MMPI is absorbed.
 3. The stentaccording to claim 1 in which the polymer in the coating when swollenwith water containing pyrene has hydrophobic domains observable by anI3:I1 ratio of more than 0.8 preferably about
 1. 4. The stent accordingto claim 1 in which on at least the outer wall of the stent the coatingcomprises an inner layer of the said amphiphilic polymer, and, adheredto said inner layer, crystalline MMPI.
 5. The stent according to claim1, wherein X has a formula selected from II, IV, and V,—X¹—R⁴—N⁺(R⁵)₂—R⁶—V  II, wherein X¹ is a valence bond, —O—, —S— or —NH—,V is a carboxylate, sulphonate or phosphate (diester-monovalentlycharged) anion; R⁴ is a valence bond (together with X¹), or alkylene—C(O)alkylene-, or —C(O)NHalkylene; the groups R⁵ are the same ordifferent and each is hydrogen or alkyl of 1 to 4 carbon atoms or thegroups R⁵ together with the nitrogen to which they are attached form aheterocyclic ring of 5 to 7 atoms; and R⁶ is alkylene of 1 to 20;

wherein X² is a valence bond, —O—, —S— or —NH—, R⁹ is a valence bond(optionally together with X²), or alkylene, —C(O)alkylene- or—C(O)NHalkylene; and the groups R⁸ are the same or different and each ishydrogen or alkyl of 1 to 4 carbon atoms, or two of the groups R⁸,together with the nitrogen to which they are attached, form aheterocyclic ring of from 5 to 7 atoms, or the three group R⁸ togetherwith the nitrogen atom to which they are attached form a fused ringstructure containing from 5 to 7 atoms in each ring;

wherein the moieties X³ and X⁴, which are the same or different, are—O—, —S—, —NH— or a valence bond, and W+ is a group comprising anammonium, phosphonium or sulphonium cationic group and a group linkingthe anionic and cationic moieties.
 6. The stent according to claim 5,wherein for formula II: X¹ is —O—; R⁴ is C₁-C₆ alkylene; and R⁶ is C₁-C₆alkylene; for formula IV: X² is —O—; the groups R⁸ are methyl; and R⁹ isC₁-C₆ alkylene; for formula V: X³ and X⁴ are —O—; and the group linkingthe anionic and cationic moieties is a C₁₋₁₂-alkanediyl group.
 7. Thestent according to claim 1, wherein X has a formula V,

wherein W contains as cationic group an ammonium group; the group W⁺ isselected from the group of formula —W¹—N⁺R¹⁰ ₃, —W¹—P⁺R¹¹ ₃, —W¹—S⁺R¹¹₂, or —W¹—Het⁺; wherein W¹ is alkanediyl of 1 or more carbon atoms,optionally containing one or more ethylenically unsaturated double ortriple bonds, disubstituted-aryl, alkylene aryl, aryl alkylene, oralkylene aryl alkylene, disubstituted cycloalkyl, alkylene cycloalkyl,cycloalkyl alkylene or alkylene cycloalkyl alkylene, which group W¹optionally contains one or more fluorine substituents and/or one or morefunctional groups; either the groups R¹⁰ are the same or different andeach is hydrogen or alkyl of 1 to 4 carbon atoms, preferably methyl, oraryl, or two of the groups R¹⁰ together with the nitrogen atom to whichthey are attached form a heterocyclic ring containing from 5 to 7 atomsor the three groups R together with the nitrogen atom to which they areattached form a fused ring structure containing from 5 to 7 atoms ineach ring, and optionally one or more of the groups R¹⁰ is substitutedby a hydrophilic functional group, the groups R¹¹ are the same ordifferent and each is R¹⁰ or a group OR¹⁰, where R¹⁰ is as definedabove; and Het is an aromatic nitrogen-, phosphorus-, or sulphur-. 8.The stent according to claim 7, wherein W¹ is C₂-C₆ alkanediyl, arylgroup is phenyl, and Het group is pyridinyl.
 9. The stent according toclaim 7, wherein W¹ is ethane-1,2-diyl.
 10. The stent according to claim1, wherein X has a formula of III

wherein the groups R⁷ are the same or different and each is hydrogen orC₁₋₄ alkyl, and d is from 2 to
 4. 11. The stent according to claim 10,wherein the groups R⁷ are the same.
 12. The stent according to claim 10,wherein the groups R⁷ are both methyl.
 13. The stent according to claim1, wherein X has a formula of VI,

wherein the groups R¹² are the same or different and each is hydrogen orC₁₋₄ alkyl, and e is from 1 to
 4. 14. The stent according to claim 13,wherein the groups R¹² are the same.
 15. The stent according to claim13, wherein the groups R¹² are all methyl.
 16. The stent according toclaim 1, wherein R¹³ is a straight or branched alkyl, alkoxyalkyl oroligoalkoxyalkyl chain containing 4 or more, preferably 6 to 24 carbonatoms, unsubstituted or substituted by one or more fluorine atomsoptionally containing one or more carbon double or triple bonds; or asiloxanegroup —(CR¹⁸ ₂)_(qq)(SiR¹⁹ ₂)(OSiR¹⁸ ₂)_(pp)R¹⁹ in which eachgroup R¹⁸ is the same or different and is hydrogen or alkyl of 1 to 4carbon atoms, or aralkyl, for example benzyl or phenethyl, each groupR¹⁹ is alkyl of 1 to 4 carbon atoms, qq is from 1 to 6 and pp is from 0to
 49. 17. The stent according to claim 16, wherein R¹³ is a straightalkyl having 4 to 18 carbon atoms.
 18. The stent according to claim 1,wherein R²⁰ is selected so as to be reactive with itself or with afunctional group in the polymer or at a surface to be coated.
 19. Thestent according to claim 18, wherein R²⁰ is selected from the groupconsisting of ethylenically and acetylenically unsaturated groupscontaining one or more radicals; aldehyde groups; silane and siloxanegroups, each containing one or more substituents selected from halogenatoms; C₁₋₄-alkoxy groups; hydroxyl; amino; carboxyl; epoxy; —CHOHCH₂Hal(in which Hal is selected from chlorine, bromine and iodine atoms);succinimido; tosylate; triflate; imidazole carbonyl amino; optionallysubstituted triazine groups; acetoxy; mesylate; carbonyl di(cyclo)alkylcarbodiimidoyl; isocyanate, acetoacetoxy; and oximino.
 20. The stentaccording to claim 18, wherein R²⁰ comprises a silane group containingat least one substituent selected from halogen atoms and C₁₋₄-alkoxygroups.
 21. The stent according to claim 1, wherein B and B² areindependently straight chain C₂₋₈-alkanediyl.
 22. The stent according toclaim 1, wherein the polymer has a formula of formula X or a saltthereof,

wherein R¹⁴ is hydrogen or a C₁-C₄ alkyl group; A^(l) is —O— or —NR¹⁵—;R¹⁵ is hydrogen, a C₁-C₄ alkyl group or R¹³; R²¹ is hydrogen or a C₁-C₄alkyl group; A² is —O— or —NR²²—; R²² is hydrogen, a C₁-C₄ alkyl groupor B²R²⁰; and each R²⁰ is a independently a cross-linkable group. 23.The stent according to claim 1, wherein the MMPI is a hydroxamic acidbased collagenase inhibitor which is an oligopeptide compound of thegeneral formula XI

wherein: a is an integer having the value 0, 1 or 2; and R³¹ representsa hydrogen atom, C₁₋₆ alkyl, phenyl, thienyl, substituted phenyl,phenyl(C₁₋₆)alkyl, heterocyclyl, (C₁₋₆)alkylcarbonyl, phenacyl orsubstituted phenacyl group; or when a=0, R³¹ represents R^(x), whereinR^(x) represents a group:

R³² represents a hydrogen atom or a C₁₋₆ alkyl, C₁₋₆ alkenyl,phenyl(C₁₋₈) alkyl, cycloalkyl(—C₁₋₆)alkyl or cycloalkenyl(C₁₋₆)alkylgroup; R³³ represents an amino acid side chain or a C₁₋₆ alkyl, benzyl,(C₁₋₆ alkoxy) benzyl, benzyloxy(C₁₋₆ alkyl) or benzyloxbenzyl group; R³⁴represents a hydrogen atom or a methyl group; A³ represents a C₁₋₆hydrocarbon chain, optionally substituted with one or more C₁₋₆ alkyl,phenyl or substituted phenyl groups.
 24. The stent according to claim15, wherein R³³ represents an amino acid side chain which is acharacteristic side chain attached to the —CH(NH₂)(COOH) moiety in thefollowing R or S amino acids: glycine, alanine, valine, leucine,isoleucine, phenylalanine, tyrosine, tryptophan, serine, threonine,cysteine, methionine, asparagine, glutamine, lysine, histidine,arginine, glutamic acid and aspartic acid.
 25. The stent according toclaim 1, wherein the MMPI is batimastat or marimastat.
 26. The stentaccording to claim 1, wherein the MMPI is present in an amount in therange of 1 μg to 1000 μg per stent.
 27. A method for producing a drugcoated intravascular stent according to claim 1, said method comprising:a) coating a metallic stent body on its inner and outer walls with thecross-linkable amphiphilic polymer; b) subjecting the cross-linkablepolymer to conditions under which cross-linking takes place to produce apolymer-coated stent; c) contacting at least the outer coated wall ofthe polymer coated stent with a liquid drug composition comprising asparingly water-soluble matrix metalloproteinase inhibitor (MMPI) and anorganic solvent in which the MMPI is at least partially dissolved andwhich is capable of swelling the cross-linked polymer of the coating,for a time sufficient to swell the polymer coating on the outer wall, toproduce a wet drug-coated stent; and d) evaporating the organic solventfrom the wet drug-coated stent to produce a dry drug-coated stent. 28.The method according to claim 27, wherein, in step c), the MMPI is bothabsorbed into the polymer and adsorbed at the surface of the polymercoating, whereby, upon evaporation of the solvent in step d), crystalsof the MMPI are formed which are adherent to the surface of the drydrug-coated stent.
 29. The method according to claim 27, wherein, instep c), the contacting is by dipping the polymer coated stent in theliquid drug composition, optionally repeatedly dipping.
 30. The methodaccording to claim 27, wherein in step c), the contacting is by flowing,spraying or dripping the liquid drug composition onto the stent, andimmediately allowing evaporation of the solvent from the wet drug-coatedstent in step d).
 31. The method according to claim 28, wherein thestent is, between steps b) and c), mounted onto the stent deliverysection of a stent-delivery catheter, whereby the stent delivery sectionis also contacted with the liquid drug composition.
 32. The methodaccording to claim 31, wherein the stent-delivery catheter is a ballooncatheter in which the balloon is formed of polyamide, and wherein theorganic solvent in the liquid drug composition is selected fromdimethylsulphoxide, dichloromethane, C₁₋₄ alcohol, and admixturesthereof.
 33. The stent according to claim 16, wherein R¹³ is a straightalkyl having 12 to 16 carbon atoms.
 34. The stent according to claim 1,wherein the MMPI is present in an amount in the range 10 μg to 150 μgper stent.